Fast signal conductor networks for programmable logic devices

ABSTRACT

A programmable logic integrated circuit device has a plurality of areas of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns of such areas. A so-called “fast conductor” network is provided on the device for rapidly and efficiently distributing a relatively small number of signals to substantially any logic area on the device. The fast conductor network has several main conductors that substantially bisect the array in one direction (e.g., by extending parallel to the column axis). Some main conductors can carry signals from off the device. Other main conductors can carry signals generated on the device. The network further includes secondary conductors that extend transverse to the main conductors (e.g., along each row of logic areas). Programmable logic connectors are provided for selectively applying signals from the main conductors to the secondary conductors and from the secondary conductors to the logic areas.

[0001] This application is a continuation of U.S. patent application Ser. No. 09/765,796, filed Feb. 28, 2001, which is hereby incorporated by reference herein in its entirety, and which is a continuation of U.S. patent application Ser. No. 09/287,048, filed Apr. 6, 1999, which claims the benefit of United States provisional patent application No. 60/109,417, filed Nov. 18, 1998.

BACKGROUND OF THE INVENTION

[0002] This invention relates to programmable logic integrated circuit devices, and more particularly to the organization of particular types of interconnection conductors on such devices.

[0003] Programmable logic devices with areas of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns of such areas are well known as shown, for example, by Cliff et al. U.S. Pat. No. 5,689,195, which is hereby incorporated by reference herein in its entirety. Advances in integrated circuit fabrication technology are making it possible to make such programmable logic devices both larger and denser. For example, more and more areas of programmable logic can be put on such devices by making the device larger, or denser, or both larger and denser.

[0004] Many desired uses of programmable logic devices require certain signals to be supplied to many logic areas. For example, many logic areas may need to receive the same register clocking or register clearing (“control”) signals. Or many areas may need to receive the same “data” signal. In some cases each of several data or control signals may need to go to respective different groups of logic areas, each such group including many areas. Some of the data or control signals requiring dispersion to many logic areas may need to come from outside the device, while others may need to be generated on the device.

[0005] Efficient networks are needed for allowing flexible distribution of very wide fan-out signals of the type described above. Because such a network must extend so extensively throughout the device, the number of conductors in the network should be kept relatively low to avoid devoting an undue proportion of the total resources of the device to these conductors and the connections from these conductors to each logic area on the device. The network should also preferably be designed for rapid dissemination of the signals on the network because these widely used signals should not hold back the operating speed of the device. In fact, a network of this type may be called a “fast conductor” or “fast signal” network to indicate the desirability of rapid propagation of signals on the network. The network should allow signals to reach any logic area on the device with relatively little delay, and there should also be relatively little “skew” associated with the network. (Skew refers to different amounts of delay being associated with reaching different logic areas on the device.)

[0006] In view of the foregoing, it is an object of this invention to provide improved fast conductor networks for programmable logic devices.

[0007] It is a more particular object of this invention to provide fast conductor networks which require relatively small amounts of the overall resources of the device, but which are capable of rapidly and flexibly distributing either external or internal signals throughout the device with relatively little skew.

SUMMARY OF THE INVENTION

[0008] These and other objects of the invention are accomplished in accordance with the principles of the invention by providing a fast conductor network for a programmable logic device that has a plurality of areas of programmable logic disposed on the device in a two-dimensional array of intersecting rows and columns of such areas. The fast conductor network preferably includes several main conductors that extend across the device so as to bisect the device (e.g., by extending parallel to the columns of logic areas at a location which bisects each row of the logic areas). Some of these main conductors receive signals from input pins of the device. These input pin connections are preferably relatively direct and “dedicated” to help reduce delay. (A dedicated connection is one which goes only to a conductor in the fast conductor network and which therefore does not require switching or have other uses that can increase the associated signal loading and delay.) Others of these main conductors receive signals from logic areas on the device. The logic areas that can supply signals to the main conductors are preferably adjacent to the main conductors to help reduce delay associated with disseminating those signals. Drivers may be provided in the main conductors to help strengthen and speed the signals on these conductors.

[0009] Assuming that the main fast conductors extend parallel to the columns of logic areas, then several secondary fast conductors are associated with each row of the logic areas. The secondary fast conductors associated with each row extend along that row. Programmable logic connectors (“PLCs”) are associated with each row's group of secondary fast conductors for selectively applying signals from the main conductors to the secondary conductors. Additional PLCs are associated with each logic area for selectively applying signals from that row's group of secondary fast conductors to that area's logic. These connections are preferably such that the fast signals can be used by the receiving area either as data or as control signals. For example, a data signal can be one of the “logic” inputs applied to a look-up table in the logic area to cause the look-up table to select and output a logic output signal. Alternatively, a control signal to a logic area can control a function of a register in the area. Examples of register functions that may be thus controlled are clocking or clearing the register.

[0010] Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a simplified block diagram of representative portions of an illustrative programmable logic array integrated circuit device which can be constructed in accordance with the invention.

[0012]FIG. 2 is a simplified schematic block diagram of representative portions of the FIG. 1 device showing additional features of that device.

[0013]FIG. 3 is a more detailed but still simplified schematic block diagram of representative portions of the FIG. 1 device showing still more features of that device.

[0014]FIG. 4 is a more detailed but still simplified schematic block diagram of representative portions of an illustrative embodiment of a fast conductor network in accordance with this invention on a device of the type shown in FIG. 1.

[0015]FIG. 5 is a more detailed but still simplified schematic block diagram of representative portions of the FIG. 4 circuitry showing further features of that circuitry.

[0016]FIG. 6 is a more detailed but still simplified schematic block diagram of a representative portion of the FIG. 1 device showing other aspects of that device.

[0017]FIG. 7 is a more detailed but still simplified schematic block diagram of a representative portion of the FIG. 1 device showing still other aspects of that device.

[0018]FIG. 8 is a more detailed but still simplified schematic block diagram of portions of the circuitry shown in FIG. 7.

[0019]FIG. 9 is a more detailed but still simplified schematic block diagram of a representative portion of the FIG. 1 device showing still other aspects of that device.

[0020]FIG. 10 is a simplified schematic diagram of a representative portion of the FIG. 9 circuitry.

[0021]FIG. 11 (consisting of part 11 a on the left and part 11 b on the right) is a more detailed but still simplified schematic block diagram of the FIG. 9 circuitry.

[0022]FIG. 12 is a simplified schematic block diagram of a representative portion of the FIG. 1 device showing still further aspects of that device.

[0023]FIG. 13 is a simplified block diagram of an illustrative system employing a programmable logic device in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In the preceding sections of this specification a programmable logic device is referred to as having “areas” of programmable logic. These logic areas are most nearly analogous to the “super-regions” 20 of programmable logic in the illustrative embodiment that will now be described. It will be understood, however, that unless otherwise indicated, the term “logic area” as used herein and in the appended claims is intended to be generic to an area of logic of any type, size, or complexity. For example, in other embodiments of the invention a logic area can be more like a “region” 30 or 40 or a “subregion” 50 in the illustrative embodiment that will now be described.

[0025] As shown in FIG. 1, an illustrative programmable logic device 10 which can be constructed in accordance with this invention includes 112 super-regions 20 of programmable logic and memory disposed on the device in a two-dimensional array of 28 rows and four columns of super-regions. Each row includes four super-regions and each column includes 28 super-regions. The fourteenth row from the top is a “spare” row that is used only when it is necessary to make up for a defect in one of the thirteen rows above that spare row. Similarly, the fourteenth row from the bottom is a spare row that is used only when it is necessary to make up for a defect in one of the thirteen rows below that spare row. A certain amount of “redundancy” is thus provided on device 10.

[0026] Each super-region 20 includes a row of 16 regions 30 of programmable logic and one region 40 of memory, which the user of device 10 can use as RAM, ROM, etc.

[0027] Each logic region 30 includes a column of ten subregions 50 of programmable logic. To avoid over-crowding FIG. 1, only the extreme upper left-hand logic region 30 has its subregions 50 shown separately.

[0028]FIG. 1 also shows that each row of super-regions 20 (except the spare rows) has “horizontal” input/output (“I/O”) pins 60 adjacent each end of the row. The top-most and bottom-most rows have four I/O pins 60 adjacent each end, while all the other non-spare rows have five I/O pins 60 adjacent each end. “Vertical” I/O pins 70 are similarly provided at each end of each column of logic regions 30. In general, two I/O pins 70 are provided at each end of each such column, except that in each super-region column only one I/O pin 70 is provided at each end of the extreme left-most and right-most column of logic regions 30.

[0029] In FIG. 1 the horizontal line 80 and the vertical line 90 divide the circuitry into four equal-sized quadrants. Lines 80 and 90 represent segmentation buffers in certain interconnection conductors as will be shown and described in more detail below.

[0030]FIG. 2 is an over-view of the higher levels in the interconnection conductor resources on device 10. FIG. 2 shows that there are vertical conductors 100 associated with each column of super-regions 20 and horizontal conductors 110 associated with each row of super-regions 20. For example, there may be 80 vertical conductors 100 associated with each column of logic regions 30 (FIG. 1) and 208 vertical conductors 100 associated with each column of memory regions 40 (FIG. 1). There may be 100 horizontal conductors 110 associated with each row of super-regions 20. Vertical conductors 100 allow communication to, from, and between the super-regions 20 in the associated super-region column. Horizontal conductors 110 allow communication to, from, and between the super-regions 20 in the associated super-region row.

[0031] Each vertical conductor 100 is segmented at its midpoint by programmable segmentation buffers 120 a and 120 b. Each segmentation buffer 120 is controlled by an associated programmable function control element (“FCE”) 122 a or 122 b. The FCEs 122 associated with a vertical conductor 100 can be programmed to disable both of the associated buffers 120, in which case each half of the conductor 100 can be used separately and independently. Alternatively, either one of the FCEs 122 associated with a conductor 100 can be programmed to enable the associated buffer 120, in which case one half of the conductor drives the other half. For example, if the buffer 120 a of a conductor 100 is enabled, the upper half of that conductor drives the lower half. In this way the two halves of a conductor 100 can be used together.

[0032] Each horizontal conductor 110 is similarly segmented at its midpoint by segmentation buffers 130 a and 130 b, respectively controlled by FCEs 132 a and 132 b. Operating in the same way as elements 120 and 122, elements 130 and 132 allow each half of a conductor 110 to be used separately, or allow either half of such a conductor to drive the other half.

[0033]FIG. 2 also shows that each super-region 20 has a plurality of “global horizontal” conductors 140 for conveying signals to, from, and between the logic and memory regions 30 and 40 (FIG. 1) in the associated super-region. (Although conductors 140 are sometimes called “global” because they span all the regions 30 and 40 in the associated super-region 20, from a larger perspective they are actually less global than above-described conductors 100 and 110, which span multiple super-regions 20.) In the particular embodiment being described there are 279 conductors 140 uniquely or exclusively associated with each super-region 20.

[0034]FIG. 3 shows the interconnectivity within a typical super-region 20. Local conductors, in general of two different kinds 160 a and 160 b, extend along each side of each logic or memory region 30 or 40 (FIG. 1). Local conductors 160 a are region-feeding conductors that bring signals from associated conductors 140 and 150 into closer proximity to the inputs of the adjacent logic or memory regions 30/40 (FIG. 1). Conductors 150, which have not been previously mentioned, are part of a network of clock and “fast” conductors that extends throughout device 10 in order to provide universal or at least wide availability of signals such as clocks, clears, and/or other signals that may be needed at many locations on the device. Programmable logic connectors (“PLCs”) 170 are provided for programmably selectively connecting conductors 140/150 to conductors 160 a. Local conductors 160 b are local feedback conductors for making available to adjacent or nearby subregions 50 (FIG. 1) the output signals of each subregion 50. Conductors 180 are provided for selectively applying signals from conductors 160 to the inputs of the adjacent logic or memory regions 30/40 (FIG. 1). Although not shown in FIG. 3 (to avoid over-crowding the drawing), PLCs are provided for programmably selectively connecting intersecting conductors 160 and 180. Thus intersections between conductors 160 and 180 represent these PLCs. A few representative ones of these intersections are numbered 162.

[0035] The outputs of logic and memory regions 30/40 (FIG. 1) are applied to various types of drivers, some of which are shown in FIG. 3. Not shown in FIG. 3 (but shown elsewhere) are drivers for selectively applying logic and memory region outputs to adjacent local feedback conductors 160 b. Other drivers 190 associated with each region 30/40 (FIG. 1) selectively apply region outputs, as well as signals from adjacent conductors 100 and 110, to adjacent conductors 140. Still other drivers 200 associated with each region 30/40 (FIG. 1) selectively apply region outputs, as well as signals from adjacent conductors 100 and 110, to other adjacent conductors 100 and 110.

[0036]FIG. 3 also shows that the conductors 100 associated with each column of memory regions 40 (FIG. 1) are divided into two groups: regular conductors 100 and tri-state conductors 100′. Each memory region 40 in a column has a tri-state driver 210 for programmably selectively applying an output of that memory region to selected ones of the tri-state conductors 100′ associated with that column. Drivers 210 and conductors 100′ are used when several memory regions in a column are being used together to provide a deeper memory than can be provided by one memory region alone. See Pedersen U.S. Pat. No. 6,072,332 for additional information regarding this type of use of several memory regions together. The just-mentioned Pedersen reference is hereby incorporated by reference herein in its entirety.

[0037]FIG. 4 is a further depiction of the network of fast conductors shown in part by conductors 150 in FIG. 3. (FIG. 4 does not show the clock conductors that are among the conductors 150 shown in FIG. 3.) Eight fast trunk or main conductors 220 a/b extend vertically across device 10 so as to bisect the two-dimensional array of super-regions 20. Four of these trunk conductors 220 a extend from dedicated fast input pins 230. The other four trunk conductors 220 b can be driven from tri-state drivers 240 in super-regions 20 to the left and right of those conductors. PLCs 246 are provided for each row of super-regions 20 for applying to each of the fast conductors 150 associated with that row a signal from either one of the conductors 220 a driven from a pin 230 or one of the conductors 220 b driven from a tri-state driver 240. Each of conductors 220 a/b has a buffer 250 at its midpoint. In the case of each conductor 220 b that is drivable from a tri-state driver 240, buffers 250 a and 250 b are provided in each direction, and an FCE 252 is provided for programmably enabling one of those drivers while disabling the other driver.

[0038]FIG. 5 shows additional details of the clock and fast conductor network. In particular, FIG. 5 shows that each of tri-state drivers 240 gets its input signal from any of the conductors 160 a and 160 b that are closest to the center of device 10 (and therefore to conductors 220 b) and that are adjacent to that driver. PLCs 241 and a conductor 241′ supply the input signal to each driver 240. Each driver 240 is controlled by an associated FCE 242. The output of each driver 240 is applied to one or more of the associated conductors 220 b by PLCs 244.

[0039]FIG. 5 shows that each of the four fast conductors 150 associated with each row of super-regions 20 can be driven from either a respective one of the four conductors 220 a that come from dedicated fast input pins 230 or a respective one of the four conductors 220 b that are drivable by tri-state drivers 240. PLCs 246 make these selections and drivers 248 drive the selected signals onto fast conductors 150.

[0040]FIG. 5 also shows circuitry 260 associated with each region for deriving so-called secondary signals for the region from among two clock and four fast conductors 150 and four inputs 180 from the adjacent conductors 160. These secondary signals are used for controlling registers in the subregions 50 of the associated region 30. For example, the secondary signals provide signals such as clocks and clears that may be needed by the registers.

[0041]FIG. 5 still further shows the drivers 270 that are used to drive subregion outputs onto the adjacent local feedback conductors 160 b. More typical examples of drivers 270 are shown in FIG. 7, and so further discussion of these drivers is deferred until that FIG. is considered.

[0042] The two clock conductors 150 shown in FIG. 5 (i.e., the top two horizontal conductors in FIG. 5) are part of a clock conductor network that extends throughout device 10 from two dedicated clock input pins. It is not believed necessary to provide a more extensive depiction or description of the clock conductor network because that network can take many forms and because the form of that network is not critical to the present invention.

[0043] An illustrative subregion 50 is shown in more detail (although still simplified) in FIG. 6. Further detail regarding possible constructions of subregion 50 can be found in Cliff et al. U.S. Pat. No. 5,999,015, which is hereby incorporated by reference herein in its entirety. However, such further detail is not believed necessary for an understanding of the present invention.

[0044] As shown in FIG. 6, subregion 50 includes a four-input look-up table 310 which is programmable to produce an output signal that is any logical combination of the four input signals 180 applied to the look-up table. The look-up table output signal can be registered by register 320. Secondary signals (e.g., clocks and clears from associated circuitry 260 in FIG. 5) are also applied to register 320. The output signal of register 320 is applied to one input terminal of each of PLCs 330 a and 330 b. The unregistered output signal of look-up table 310 is applied to the other input terminal of each of PLCs 330 a and 330 b. Thus each of PLCs 330 a and 330 b is programmable to produce an output signal 340 a or 340 b, respectively, which is either the registered or unregistered output signal of look-up table 310.

[0045]FIG. 7 shows in more detail that each subregion 50 receives two of its primary inputs 180 from the conductors 160 to its left and the other two of its primary inputs 180 from the conductors 160 to its right. FIG. 7 also shows that each subregion 50 applies one of its primary outputs 340 a to the drivers 190/200/270 to its left and the other of its primary outputs 340 b to the drivers 190/200/270 to its right. Each driver group 190/200/270 receives outputs 340 from four subregions 50, two to its left and two to its right. The portion 270 of each driver group 190/200/270 produces two local output signals 350 a and 350 b that are applied to two of the conductors 160 b that are adjacent to the region 30 that includes that driver group. Each of output signals 350 is selected from the outputs 340 of two horizontally adjacent subregions 50 (see also FIG. 8 which illustrates this last point more clearly). In half the super-regions 20, circuitry of the type shown in FIG. 7 appears in left/right mirror image from what is shown in FIG. 7.

[0046]FIG. 8 shows additional details of representative driver groups 190/200/270. For example, PLC 410 is programmable to select one signal from among the output signal 340 b of the adjacent upper left subregion 50, the output signal 340 a of the adjacent lower right subregion 50, ten adjacent vertical conductor signals 100, and one adjacent horizontal conductor signal 110. The signal selected by PLC 410 is applied to driver 412 and then to an adjacent global conductor 140. PLC 420 is programmable to select one signal from among the output signal 340 b of the adjacent upper left subregion 50, the output signal 340 a of the adjacent lower right subregion 50, eight adjacent vertical conductor signals 100, and one adjacent horizontal conductor signal 110. The signal selected by PLC 420 is applied to driver 422 and then (via PLC 424) to one of three adjacent vertical conductors 100 or one of two adjacent horizontal conductors 110.

[0047] PLC 430 is programmable to select one signal from among the output signal 340 b of the adjacent upper left subregion 50, the output signal 340 a of the adjacent upper right subregion 50, twelve adjacent vertical conductor signals 100, and one adjacent horizontal conductor signal 110. The signal selected by PLC 430 is applied to driver 432 and then to an adjacent global horizontal conductor 140.

[0048] Elements 440, 442, and 444 are generally similar to elements 420, 422, and 424 except that the applied subregion outputs are from the adjacent lower left and upper right subregions 50. Elements 450 and 452 are similar to elements 410 and 412 except that the applied subregion outputs are from the adjacent lower left and upper right subregions 50.

[0049]FIG. 8 also shows that local feedback output signal 350 a is selected (by PLC 460) from the output 340 b of the adjacent upper left subregion 50 and the output 340 a of the adjacent upper right subregion 50. Driver 462 strengthens the signal selected by PLC 460. Local feedback output signal 350 b is selected (by PLC 470) from the output 340 b of the adjacent lower left subregion 50 and the output 340 a of the adjacent lower right subregion 50.

[0050] It will be noted that FIG. 8 shows upper left and upper right subregions 50 having more ways out to conductors 100, 110, and 140 than lower left and lower right subregions 50. This apparent disparity can be equalized by giving the lower left and lower right subregions more ways out in the driver groups 190/200 to the left and right of the driver group shown in FIG. 8, while the upper left and upper right subregions are given fewer ways out in the driver groups 190/200 to the left and right. By alternating in this way horizontally across the row of regions 30 in each super-region 20, and by also similarly alternating vertically down the columns of subregions 50 in each super-region 20, approximate homogeneity in the output access of all subregions 50 is achieved.

[0051] A representative memory region 40 is shown in more detail in FIG. 9. Certain principles of memory region construction that are shown and described in Cliff et al. U.S. Pat. No. 5,550,782, Cliff et al. U.S. Pat. No. 5,689,195, and Heile U.S. Pat. No. 6,020,759 can be used in memory region 40. Thus additional details regarding certain aspects of memory region 40 can be found in those other references, all of which are hereby incorporated by reference herein in their entireties. However, it is not believed that those additional details are necessary for an understanding of the present invention.

[0052] The main component of memory region 40 is a block 510 of 64 rows and 32 columns of RAM bits. (Other possible uses of memory region 40 (e.g., for ROM, product term (“p-term”) logic, etc.) will be understood to be included by references to RAM.) Circuitries 540 and 600 are each programmable (by associated FCEs that are not shown) to enable memory region 40 to operate in any one of several different word length modes. The word length choices available to the user are one bit, two parallel bits, four parallel bits, eight parallel bits, and 16 parallel bits.

[0053] As many as five bits of write address information are applied to circuitry 540 via leads 512. As many as 16 bits of write data are applied to circuitry via leads 514. If a word length less than 16 has been selected, leads 514 that are not needed for data are used for additional read/write column address bits. Circuitry 540 uses the information applied to it via leads 512/514 and its programmed word length state to enable one or more columns of RAM block 510 via leads 542 and to route data from leads 514 to appropriate ones of leads 544. Six additional bits of write address information are applied to write address decoder circuitry 550 via leads 516. Circuitry 550 uses this information to enable one of the 64 rows of RAM block 510 via AND gates 560 and leads 562 when AND gates 560 are enabled by a write enable signal on lead 518. The data applied via leads 544 is thereby stored in RAM block 510 in the column(s) enabled via leads 542 at the row enabled via leads 562.

[0054] Memory region 40 can be read in either of two different modes: RAM mode or p-term mode. considering RAM mode first, six bits of read address information are applied to read address decoder 570 via leads 520. Decoder 570 uses this information to select one of the 64 rows of RAM block 510 when AND gates 580 are enabled by a read enable signal on lead 522. In RAM mode PLCs 590 are programmed to apply the output signals of AND gates 580 to read enable leads 592 of RAM block 510. The data read from the RAM block row that is thus enabled is output via leads 598. Circuitry 600 receives as many as five more bits of read address information via leads 524. Circuitry 600 uses this information and its programmed state (indicative of the word length selection made by the user as described earlier) to select one, two, four, eight, or 16 data bits for output via leads 602.

[0055] In p-term mode 32 bits of a so-called “p-term literal” are assembled on leads 530 from the 16 leads 514, the six leads 516, the six leads 520, and four leads 526 that are otherwise used for high order read address signals. As is explained in more detail in above-mentioned Pedersen U.S. Pat. No. 6,072,332, these high order address bits are used when several memory regions 40 in a column are used together to provide a deeper memory than can be provided by one memory region alone. The signals on leads 530 are inverted by inverters 532, and both the true and complement versions of the lead 530 signals are applied to PLCs 590 via leads 534. In p-term mode PLCs 590 are programmed to apply the signals on leads 534 to leads 592. Accordingly, half the rows in RAM block 510 are read simultaneously, the rows thus read being determined by which bits of the p-term literal on leads 530 are logic 1 and which bits are logic 0. Each column in RAM block 510 outputs via the associated lead 598 the product of the data stored in the rows that are enabled. OR gates and related elements in circuitry 600 allow sums of the products on leads 598 to be formed and output via leads 602. Thus in p-term mode memory region 40 produces sum-of-products output signals on leads 602.

[0056]FIG. 10 shows an illustrative construction of one representative memory cell in RAM block 510. Inverters 710 and 720 are connected in a closed loop series to store one bit of data. Data can be written into inverters 710/720 by applying that data in true and complement form to leads 544 and 544 bar, respectively, and by applying logic 1 to write column select lead 542 and row write lead 562. These logic 1 signals enable transistors 730, 740, 750, and 760, thereby causing inverters 710/720 to store the applied data.

[0057] Data can be read from inverters 710/720 by applying logic 1 to row read lead 592. This enables transistor 780. If transistor 770 is also enabled by a logic 1 output from inverter 710, a conductive path is established between source line 598 a and drain line 598 b. A sense amplifier (600 in FIG. 9) senses whether there is such a conductive path between lines 598 a and 598 b.

[0058]FIG. 11 shows how a representative memory region 40 is connected to the adjacent interconnection conductors. FIG. 11 shows a memory region 40 which is part of a super-region 20 in which the logic regions 30 are to the left of the memory region. If the logic regions 30 were to the right of memory region 40, the circuitry would be a mirror image of FIG. 11. For convenience herein the side of memory region 40 toward the adjacent logic regions 30 is sometimes called the “region side” of the memory region. The side of memory region 40 which is remote from the adjacent logic regions 30 is sometimes called the “super-region side” of the memory region.

[0059] The signals that are data signals 514 in FIG. 9 come from circuitry 810 in FIG. 11. Circuitry 810 is a group of registers that can be either (1) used to register signals from the leads 180 feeding that circuitry from the logic region side of memory region 40, or (2) bypassed to allow unregistered connection of those leads 180 to leads 514. The data applied to RAM block 510 via leads 514 can therefore be either “registered or bypassed”, based on programmable control of circuitry 810. The “registered or bypassed” option is also available with other signals in FIG. 11 as will be described below.

[0060] Circuitry 820 receives the fast line and clock signals from leads 150, and also receives three more signals from associated leads 180 on the logic region side of memory region 40. A further input to circuitry 820 is an enable signal from circuitry 830, which decodes high order address bits that are used to control writing to a desired one of several memory regions 40 that are being used together to provide a deeper memory than a single memory region can provide. Circuitry 820 is programmable to supply several signals that are based at least in part on the inputs 150 and/or 180 and that are used elsewhere in memory region 40. For example, circuitry 820 supplies clock and clear signals for use by the registers in above-described circuitry 810. Circuitry 820 also provides the write enable signal 518 for row write address decoder circuitry 550.

[0061] Circuitry 840 provides a “registered or bypassed” option for the address signals 512 that are used for write column selection by write column decoder circuitry 540. Thus in addition to receiving five address signals, circuitry 540 receives the same clock and clear signals from circuitry 820 that circuitry 810 receives.

[0062] Circuitry 850 is similar to circuitry 820, except that it provides signals that can be used elsewhere in memory 40 primarily for output control. For example, circuitry 850 produces clock and clear signals usable by registers in “registered or bypassed” circuitries 860 and 870 and in the output stage 640 of circuitry 600. Each of circuitries 860, 870, and 640 can alternatively use the clock and clear signals from circuitry 820. Circuitry 850 receives its inputs from the super-region side of memory region 40. Circuitry 850 also receives an enable signal from circuitry 880. In providing this enable signal, circuitry 880 operates somewhat like circuitry 830. In particular, when several memory regions 40 are to be used together to provide a deeper memory than one memory region can provide, circuitry 880 receives and decodes higher order address signals to determine whether the associated memory region is the one that should currently output data. If so, circuitry 880 outputs a signal for enabling circuitry 850, which in turn applies read enable signal 522 to circuitry 590. Circuitry 860 provides a “registered or bypassed” option for the address signals that are used by circuitry 600 for read column selection. Column decoder circuitry 620 in circuitry 600 actually performs this column selection. Further column selection is performed by circuitry 630 on a programmed basis, based on whether the 16-bit, 8-bit, 4-bit, 2-bit, or 1-bit word length is in use. Circuitry 860 is programmable to use the clock and clear signals from either circuitry 820 or from circuitry 850.

[0063] Circuitry 870 provides a “registered or bypassed” option for the address bits that are used by circuitry 550 for write row selection and by circuitry 590 for read row selection. Circuitry 870 receives clock and clear signals from both circuitry 820 and circuitry 850. Circuitry 870 also passes along clock and clear signals for use by circuitry 880 in providing a “registered or bypassed” option for the higher-order address bit decoding performed by circuitry 880. Circuitry 880 can be used to apply one output from memory region 40 to one of tri-state vertical conductors 100′ via a tri-state driver 210 (FIG. 3) in circuitry 880 and via PLC 882 (e.g., a one-to-four demultiplexer). This feature is typically used when several memory regions 40 are being used together to provide a deeper memory than one memory region can provide by itself. Circuitry 880 decodes the higher-order address bits it receives via leads 180 in order to determine when to enable its tri-state driver 210 (FIG. 3).

[0064] Circuitry 640 is programmable to either pass the memory output signals selected by circuitry 630 or to form desired sums of the product terms (“p-terms”) represented by the outputs of sense amplifier circuitry 610. Additional details regarding how circuitry 630 can be constructed are shown in above-mentioned Heile U.S. Pat. No. 6,020,759. Thus circuitry 640 includes the OR circuitry needed to form various sums of the applied p-term signals. Circuitry 640 also receives the clock and clear signals from circuitries 820 and 850, and can use these signals in providing a “registered or bypassed” option for either the outputs of circuitry 630 or the sum-of-products signals generated within circuitry 640.

[0065] The driver bank 190/200/270 on the left in FIG. 11 (i.e., on the region side of memory region 40) receives (1) subregion output signals 340 b from the region 30 to the left, (2) selected outputs 602 of memory region 40, (3) signals from the vertical conductors 100 to the left, and (4) signals from the horizontal conductors 110 associated with the row of super-regions 20 that includes the memory region. This driver bank 190/200/270 is programmable to select from among these signals and drive them out onto selected ones of (1) adjacent local feedback conductors 160 b, (2) the immediately above-mentioned vertical conductors 100 and 110, and (3) the global horizontal conductors 140 associated with the super-region 20 that includes the depicted memory region 40.

[0066] The driver bank 190/200 on the right in FIG. 11 (i.e., on the super-region side of memory region 40) receives (1) all the outputs 602 of memory region 40, (2) signals from the vertical conductors 100/100′ to the right, and (3) signals from the horizontal conductors 110 associated with the row of super-regions 20 that includes the memory region. This driver bank is programmable to select from among these signals and drive them out onto selected ones of the immediately above-mentioned conductors 100 and 110 and the global horizontal conductors 140 associated with the super-region 20 that includes the depicted memory region 40.

[0067]FIG. 11 also shows the application of p-term literal signals 530 to circuitry 590. Circuitry 590 therefore also includes the inverters 532 and multiplexing 590 shown in FIG. 9.

[0068]FIG. 12 shows in more detail an illustrative construction of the two driver banks 190/200/270 and 190/200 shown in FIG. 11. The driver groups labelled “A” in FIG. 12 can be like the driver groups shown in FIG. 8. (The portion 270 of FIG. 8 is included or not in each group A in FIG. 12 depending on whether or not that group has associated local conductors 160 b that may need to be driven.) The driver groups labelled “B” in FIG. 12 are like the above-described alternative to FIG. 8 that can be alternated with the FIG. 8 driver group to produce approximate overall homogeneity to the interconnectivity provided by these drivers. FIG. 12 shows how the 16 outputs 602 of the memory region are distributed to the inputs of the various driver groups A and B, it being understood that in most cases in FIG. 12 the indicated signals 602 take the place of the correspondingly positioned subregion outputs 340 in FIG. 8. For example, in the upper left-hand driver group A in FIG. 12, the two left-hand inputs from subregions 50 are as in FIG. 8, but the two right-hand inputs are memory region outputs 602 for bit 0 and bit 2. As another example, in the upper right-hand driver group A the two individual inputs on the left are memory region outputs 602 for bit 0 and bit 1 and the two inputs on the right are memory region outputs 602 for bit 8 and bit 9. Sufficient connectivity is provided in FIG. 12 to give each memory region output 602 several different ways out to the adjacent conductors 100, 110, and 140. FIG. 12 also shows again the tri-state output to conductors 100′ via PLCs 882.

[0069] From the foregoing it will be seen that the above-described programmable logic device architecture provides a memory region 40 in association with each group of logic regions 30 on the device. Each memory region 40 can be used in conjunction with the associated logic regions 30 via relatively local interconnection resources such as conductors 140 and 160. In general, for such use of a memory region 40 with its associated logic regions 30, it is not necessary to involve more expensive, longer-length interconnection resources such as conductors 100 and 110. Although logic regions 30 and memory regions 40 are thus associated with one another in super-regions 20, all such regions can also function as global resources of the device. In particular, all logic regions 30 and memory regions 40 also have access to interconnection resources such as conductors 100 and 110 that span the device. Thus the inputs and outputs of any region 30 or 40 on the device can be connected to the inputs and outputs of substantially any other regions 30 and 40 on the device.

[0070] Fast conductor network 150/220 allows for rapid and efficient distribution of any of several so-called fast signals throughout device 10. These fast signals can come from dedicated fast input pins 230 or from super-regions 20 that are located adjacent to main fast conductors 220. Fast conductors 220 are located centrally on device 10 (i.e., so that they bisect the rows of super-regions 20). This helps reduce delay and skew of the fast signals. The fast signals can be supplied to regions 30/40 as either data signals (e.g., via leads 160 a) or as control signals (e.g., via circuitries 260, 820, or 850). Drivers such as 250 and 240 are provided to strengthen and speed the fast signals. Switching such as 241, 244, and 246 is provided to allow flexible routing of the fast signals. Sufficient fast conductors and associated switching are provided to allow different groups of super-regions 20 and/or regions 30/40 and/or subregions 50 to receive different fast signals. On the other hand, only a relatively small fraction of the overall resources of the device are devoted to the fast conductor network.

[0071]FIG. 13 illustrates a programmable logic device 10 of this invention in a data processing system 1002. Data processing system 1002 may include one or more of the following components: a processor 1004; memory 1006; I/O circuitry 1008; and peripheral devices 1010. These components are coupled together by a system bus 1020 and are populated on a circuit board 1030 which is contained in an end-user system 1040.

[0072] System 1002 can be used in a wide variety of applications, such as computer networking, data networking, instrumentation, video processing, digital signal processing, or any other application where the advantage of using programmable or reprogrammable logic is desirable. Programmable logic device 10 can be used to perform a variety of different logic functions. For example, programmable logic device 10 can be configured as a processor or controller that works in cooperation with processor 1004. Programmable logic device 10 may also be used as an arbiter for arbitrating access to a shared resource in system 1002. In yet another example, programmable logic device 10 can be configured as an interface between processor 1004 and one of the other components in system 1002. It should be noted that system 1002 is only exemplary, and that the true scope and spirit of the invention should be indicated by the following claims.

[0073] Various technologies can be used to implement the programmable logic devices of this invention, as well as the various components of those devices (e.g., the above-described PLCs and the FCEs which control the PLCs). For example, each PLC can be a relatively simple programmable connector such as a switch or a plurality of switches for connecting any one of several inputs to an output. Alternatively, each PLC can be a somewhat more complex element which is capable of performing logic (e.g., by logically combining several of its inputs) as well as making a connection. In the latter case, for example, each PLC can be product term logic, implementing functions such as AND, NAND, OR, or NOR. Examples of components suitable for implementing PLCs are EPROMs, EEPROMs, pass transistors, transmission gates, antifuses, laser fuses, metal optional links, etc. As has been mentioned, the components of PLCs can be controlled by various, programmable, function control elements (“FCEs”). (With certain PLC implementations (e.g., fuses and metal optional links) separate FCE devices are not required.) FCEs can also be implemented in any of several different ways. For example, FCEs can be SRAMs, DRAMs, first-in first-out (“FIFO”) memories, EPROMs, EEPROMs, function control registers (e.g., as in Wahlstrom U.S. Pat. No. 3,473,160), ferro-electric memories, fuses, antifuses, or the like. From the various examples mentioned above it will be seen that this invention is applicable to both one-time-only programmable and reprogrammable devices.

[0074] It will be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the number of logic units at each of the various levels in the hierarchy of logic units can differ from the specific examples mentioned herein. Similarly, the numbers of the various types of interconnection conductors and other elements can deviate from the specific examples mentioned herein. Different types and sizes of logic and memory units can be used if desired. It will also be understood that terms like “row” and “column”, “horizontal” and “vertical”, “left” and “right”, “top” and “bottom”, and other directional or orientational terms are used herein only for convenience, and that no fixed or absolute orientations are intended by the use of these terms. For example, the words in each of the word pairs mentioned above can be reversed if desired. 

The invention claimed is
 1. A programmable logic device comprising: a plurality of super-regions of programmable logic, each super-region comprising: at least one region of programable logic, each region comprising at least one subregion of programmable logic; a memory region; an inter-region interconnection conductor; first interconnection circuitry configured to selectively interconnect at least one of the subregions with a region feeding conductor; second interconnection circuitry configured to selectively interconnect the region feeding conductor and the inter-region interconnection conductor; third interconnection circuitry configured to selectively interconnect the memory region and the inter-region interconnection conductor; and the first, second, and third interconnection circuitry configured such that signals can be conveyed between the memory region and the at least one of the subregions; and fast interconnection circuitry extending to all of the super-regions and configurable to receive a plurality of fast signals from a plurality of sources and to convey to each of a plurality of multiplicities of the super-regions selected ones of the fast signals.
 2. The programmable logic device defined in claim 1 wherein the sources include a plurality of input pins.
 3. The programmable logic device defined in claim 2 wherein the sources further include selected ones of the subregions.
 4. The programmable logic device defined in claim 1 wherein the sources include selected ones of the subregions.
 5. The programmable logic device defined in claim 4 wherein each of the multiplicities of the super-regions includes at least one of the selected ones of the subregions.
 6. The programmable logic device defined in claim 1 wherein each subregion is programmable to perform a logic operation on an input signal applied to each subregion.
 7. The programmable logic device defined in claim 1 wherein each subregion is programmable to perform a control operation on an input signal applied to each subregion.
 8. The programmable logic device defined in claim 1 wherein the plurality of super-regions of programmable logic is arranged in a two-dimensional array of rows and columns.
 9. The programmable logic device defined in claim 8, the fast interconnection circuitry comprising: a plurality of horizontal super-region interconnection conductors associated with each of the rows of super-regions wherein each horizontal super-region interconnection conductor is programmable to couple any super-region in the associated row to another super-region in the associated row; a plurality of vertical super-region interconnection conductors associated with each of the columns of super-regions wherein each vertical super-region interconnection conductor is programmable to couple any super-region in the associated column to another super-region in the associated column; and a first plurality of programmable logic connectors configured to selectively interconnect the horizontal and vertical super-region interconnection conductors.
 10. A digital processing system comprising: processing circuitry; a memory coupled to said processing circuitry; and a programmable logic device as defined in claim 1 coupled to the processing circuitry and the memory.
 11. A printed circuit board on which is mounted a programmable logic device as defined in claim
 1. 12. The printed circuit board defined in claim 11 further comprising: a memory mounted on the printed circuit board and coupled to the programmable logic device.
 13. The printed circuit board defined in claim 11 further comprising: processing circuitry mounted on the printed circuit board and coupled to the programmable logic device. 